This document summarizes key aspects of populations and population growth. It discusses three important characteristics of populations: geographic distribution, density, and growth rate. It describes how populations can grow exponentially with unlimited resources but typically experience logistic growth as resources become limited. Logistic growth results in a carrying capacity where population growth stops. The document also discusses limiting factors like competition, predation, and natural disasters that can slow population growth. Finally, it provides an overview of human population growth and the factors like falling death rates that have led to exponential growth in the human population over the past 500 years.